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Unix+clones The 'no-configuration, only-active-when-needed' SSH VPN
Post date: April 12, 2005, 23:04 Category: Network Views: 40
Tutorial quote: So, we started thinking about how we might set up a VPN between the application server and our internal software mirror. The only requirement is that the VPN be initiated from the "inside-out" and that the connection is only active for as long as we need to use. In other words, it would only be active during an administration session. Ideally, it wouldn't be a lot of work to setup and tear down either.

SSH to the rescue...

Fortunately, SSH client and server come with support for this out of the box, requiring no additional software to be installed, and no configuration changes. On the server side, sshd, the setting "AllowTcpForwarding" defaults to "yes" unless your sshd_config file explicitly disables it. On the client side, all you have to do is request the forwarding.
Unix+clones Automating Perl Database Applications
Post date: May 1, 2005, 13:05 Category: Programming Views: 80
Tutorial quote: This article describes how Perl is used to generate Perl CGI code using the multi-platform CGIScripter application. The resulting output code automates SQL table creation commands (in this example, for a MySQL database), HTML pages and Perl code. Web security issues, data validation and image handling functionality are incorporated into the resulting Perl code. By automating the development of Perl CGI scripts, even entry-level developers can create CGI scripts that contain most of the commonly requested features in a short period of time--without manually writing any code.
BSD Firewalling with OpenBSD's PF packet filter
Post date: April 18, 2005, 22:04 Category: Network Views: 101
Tutorial quote: PF operates in a world which consists of packets, protocols, connections and ports.

Based on where a packet is coming from or where it's going, which protocol, connection of port it is designated for, PF is able to determine where to lead the packet, or decide if it is to be let through at all.

It's equally possible to direct network traffic based on packet contents, usually referred to as application level filtering, but this is not the kind of thing PF does. We will come back later to some cases where PF will hand off these kinds of tasks to other software, but first let us deal with some basics.

We've already mentioned the firewall concept. One important feature of PF and similar software, perhaps the most important feature, is that it is able to identify and block traffic which is you do not want to let into your local network or let out to the world outside. At some point the term 'firewall' was coined.
Linux Linux stateful firewall design
Post date: April 12, 2005, 13:04 Category: Network Views: 40
Tutorial quote: This tutorial shows you how to use netfilter to set up a powerful Linux stateful firewall. All you need is an existing Linux system that's currently using a Linux 2.4.x or 2.6.x kernel. A laptop, workstation, router or server with at a Linux 2.4.x or 2.6.x kernel will do. You should be reasonably familiar with standard network terminology like IP addresses, source and destination port numbers, TCP, UDP and ICMP, etc. By the end of the tutorial, you'll understand how Linux stateful firewalls are put together and you'll have several example configurations to use in your own projects.
RedHat My First Linux Server, Part 1
Post date: April 14, 2005, 18:04 Category: Miscellaneous Views: 100
Tutorial quote: Many small businesses are turning to Linux as way to swim against the tide of rising software costs. Are you thinking about diving into Linux for your small business? From the outside, Linux can appear to be a deep ocean of strange jargon in unchartered waters. Who has the time to wade through all that to save a few clams? With Linux, it's not a sink or swim proposition.

Linux is now a lot simpler than you may think. We can provide you with the easiest, simplest, no-problem process for installing Linux on a PC. After going through this simple installation process, you will have a basic machine that you can configure into any kind of server, workstation, or office desktop. Future articles in this My First Linux Server series will help you build productive, Linux-based servers and small office workstations.

The best choices for your first Linux machine are probably the popular Red Hat Linux or SUSE Linux, primarily because both are easy to install and configure. Additionally, these companies are sound choices for the home office or small business. Both vendors have specialized in Linux for many years and offer full corporate product lines supporting your expansion.
Linux Connecting to a Wireless LAN with Linux, Part 1
Post date: April 13, 2005, 15:04 Category: Hardware Views: 114
Tutorial quote: Wireless hardware for Linux is a moving target. The wireless network adapter that worked fine with Linux yesterday may be released with an unsupported radio chipset today, and with no indication of the change. So buyer beware--always confirm the chipset before you buy. The good news is a lot of wireless adapters have native Linux support, and for those that don't, the NdisWrapper utility lets you use the Windows drivers on your Linux box.
Linux Linux Filesystems and Partitioning: A Primer
Post date: June 24, 2005, 10:06 Category: System Views: 87
Tutorial quote: We recently to shed some light on Linux, particularly for users unfamiliar with the system. The article received quite a response from around the world and so we will be doing some follow-up articles to teach all those interested, the ins and outs of Linux. In this article, we will be discussing what partitioning is, how to choose a filesystem, how to have Windows and Linux installed on your hard drive at the same time, and more.
White+Box The perfect Setup - White Box Linux
Post date: April 15, 2005, 19:04 Category: Installing Views: 77
Tutorial quote: This is a detailed description about the steps to be taken to setup a Linux server based on White Box Linux that offers all services needed by ISPs and hosters (web server (SSL-capable), mail server (with SMTP-AUTH and TLS!), DNS server, FTP server, MySQL server, POP3/IMAP, Quota, Firewall, etc.).

Since White Box Linux is very similar to Red Hat Enterprise Linux this tutorial should also work for Red Hat Enterprise Linux.
RedHat Choosing an I/O Scheduler for Red Hat Enterprise Linux 4
Post date: July 18, 2005, 18:07 Category: Benchmarks Views: 176
Tutorial quote: The Linux kernel, the core of the operating system, is responsible for controlling disk access by using kernel I/O scheduling. Red Hat Enterprise Linux 3 with a 2.4 kernel base uses a single, robust, general purpose I/O elevator. The 2.4 I/O scheduler has a reasonable number of tuning options by controlling the amount of time a request remains in an I/O queue before being serviced using the elvtune command. While Red Hat Enterprise Linux 3 offers most workloads excellent performance, it does not always provide the best I/O characteristics for the wide range of applications in use by Linux users these days. The I/O schedulers provided in Red Hat Enterprise Linux 4, embedded in the 2.6 kernel, have advanced the I/O capabilities of Linux significantly. With Red Hat Enterprise Linux 4, applications can now optimize the kernel I/O at boot time, by selecting one of four different I/O schedulers.
Linux Optimizing Linux filesystems
Post date: April 12, 2005, 03:04 Category: Benchmarks Views: 118
Tutorial quote: Last time we introduced a few common Linux filesystems and examined their features. If you've already installed Linux, your partitions are already set up and configured with particular filesystems, but you may decide you want to modify this configuration. What's the best way to begin?